Pethidine is a frequently used analgesic. It has also a weak local anaesthetic effect. The anaesthetic/analgesic effect of pethidine after spinal administration is often insufficient in both respects. Instead combinations of bupivacaine and fentanyl or morfin are being used. The opiate analgesics have several severe draw-backs, as e.g. development of tolerance, addiction, risk for respiratory depression. There is, thus, a need for agents giving a local anaesthesia with a remaining analgesic effect. Such agents should be used after spinal or epidural injections as local anaesthetics intraoperatively. Thereafter the compounds would give good post-operative pain relief.